Method of fabricating a sleeve for joining and sealing conduits

ABSTRACT

The apparatus for joining and sealing conduits, includes edge trim, a sleeve, and a retaining element. The edge trim is shaped to mount upon and engage an end of a conduit. The sleeve extends between the conduits and at least partially surrounds the edge trim. The sleeve may be made of compressible material, such that when the retaining element surrounds a portion of the sleeve and the edge trim, the retaining element generally compresses the portion of the sleeve portion underlying the retaining element and displaces the sleeve material to expand on either side of the retaining element and limit movement of the retaining element. The method of joining and sealing conduits includes mounting the edge trim and a retaining element upon an end of a conduit, extending a sleeve between the conduits, and sliding the retaining element over the sleeve toward the end of the conduit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.10/120,614, filed Apr. 11, 2002, now U.S. Pat. No. 6,811,192 which ishereby incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

The present invention relates to joining and sealing conduits, and, inparticular, to joining and sealing conduits of various shapes in areaswith a lack of accessibility and visibility.

Conduits, such as ducts, hoses, pipes, tubes and the like are frequentlyused to transport various fluids, gases or other elements within astructure, such as a vehicle, aircraft or building. Many times theconduits are installed after the structure is partially or totallybuilt, and the conduits must be installed in pieces. The pieces of theconduits then must be joined and sealed after installation.

For example, in the aircraft industry, the environmental control systemincludes ducts to carry the fluids, gases, air, and the like required toregulate the environment of the aircraft. Typically, the environmentalcontrol system ducts are designed and installed after the aircraft ispartially or totally built, such that the duct shape must conform to theavailable space and the ducts must be installed in pieces to avoidstructural interferences. As the ducts are installed, nominal one tothree inch gaps are generally maintained between the duct segmentsdepending upon the length and material of the duct in order to allow forexpansion during operation. Thus, the ducts may be round, elliptical,square, or any other shape that fits in the available space, and thesegments of the duct must be joined and sealed in the already congestedareas of the aircraft where there is little room to access or view theentire duct joint area.

The conventional manner of joining environmental control system ductsincludes bonding elastomeric sheeting, such as flat sheets of siliconeimpregnated glass, around adjacent portions of the connecting ducts withadhesive, such as Room Temperature Vulcanized (RTV) adhesive. Theadhesive must be applied at several locations on the duct system, whichis difficult because of the limited space around the duct, thetime-sensitive nature of completing the adhesive bond, and theuniqueness of the design of the ducts.

The process of bonding the elastomeric sheeting to join the ductsrequires surface preparation, cleaning, multiple supplies, and tools. Inaddition to the supplies and tools used to apply the sheeting to theducts, an x-ray machine is also typically used to determine theintegrity of the bond between the sheeting and the duct. The x-rayphotographs of the joint area reveal where there are voids in theadhesive, uneven application of adhesive, substrate mating pressure, orother issues with the adhesive that may affect the bond between thesheeting and the duct. If the x-rays reveal a problem with the bond,then the installer must remove the sheeting and the adhesive, reapplythe adhesive and sheeting, and again x-ray the joint to determine theintegrity of the bond. This process must be repeated until the bondbetween the sheeting and the duct is acceptable.

Once the bond between the sheeting and the duct is acceptable, theelastomeric sheeting is then clamped to the ducts with metal band clampsor tie wraps. The clamps, however, do not provide uniformcircumferential pressure to the sheeting covered duct joints,particularly not to the ducts that are square or have some othernon-round shape. Thus, when a duct experiences deflection due tointernal pressure, the clamp may cause the duct surface to concave,which creates a gap and causes leakage of the elements within the duct.Deflection of the duct also may cause the duct to change shape, whichmay result in the loosening of the grip of the clamps, a break in theadhesive, and leakage of the elements contained in the ducts.Furthermore, even if the clamps remain tightly in place on the sheetingand ducts, the sharp edges of the clamp may cut into the elastomericsheeting, particularly as the ducts are subjected to the vibrations,shocks and pressures associated with the operation of an aircraft. Oncethe clamp cuts into the sheeting, the sheeting will tear and, again,cause leakage of the elements contained in the ducts.

The leaking of the elements contained in the ducts is particularlysevere in aircraft that are operated in high humidity or tropicalclimates because the environmental control system ducts contain highlevels of moisture condensation. If the ducts are not completely joinedand sealed, the fluid may leak onto electrical systems housed below theducts and through overhead ceiling panels into the passenger area orbody of the aircraft. The moisture release may require a pilot toinitiate emergency landing procedures, which includes dumping fuel for apremature landing at the nearest airport.

In order to repair the leaking duct joints, the clamps and sheeting mustbe removed and the adhesive must be cleaned off of the ducts, which isdifficult, time-consuming, and prone to damage the ducts. New adhesive,sheeting and clamps then must be re-applied to the ducts, which isanother labor-intensive and time-consuming procedure that is notguaranteed to remedy the problem. In addition, during certain mandatoryaircraft maintenance and structural checks, the entire environmentalcontrol duct system must be removed and re-installed. After repeatedrepairs and re-installations, the entire environmental control ductsystem must be replaced because of the wear and tear on the jointbonding surfaces of the ducts. Therefore, in addition to the time andexpense involved in the initial joining and sealing of the ducts, therepairs, re-installation and ultimate replacement is extremely costlybecause of the human labor and time involved, the loss of flight timefor the aircraft, and the cost of replacing the parts of the duct systemthat cannot be reused after removal.

Thus, there exists a need in the industry for an efficient manner inwhich to join and seal conduits that have inherent system issues. Inparticular, there exists a need for an efficient way to join andcompletely seal conduits of various shapes such that the deflection ofthe conduit under internal pressure will not cause leakage from thejoints, and the joints will not have to be repaired or replacedfrequently. Additionally, it would be desirable if the joints may beremoved for thorough maintenance checks and reinstalled without anexcessive investment of human labor and time, without significant lossof flight time for the aircraft, and without having to replace part orall of the conduit system.

BRIEF SUMMARY OF THE INVENTION

The apparatus and method for joining and sealing conduits of the presentinvention provide an efficient way to join, seal, and maintain conduitsthat have various shapes and/or are located in areas that are difficultto view and/or access. The apparatus and method of the present inventionalso provide an efficient manner in which to join and maintain acontinuous seal about the joints of conduits of various shapes, whichprevents the deflection of the conduit under internal pressure fromcausing leakage from the joint. As such, the conduit joints sealed bythe apparatus and method of the present invention should have to berepaired less often. Furthermore, the conduits joined and sealed by theapparatus and method of the present invention may be removed forthorough maintenance checks and reinstalled without expending largeamounts of human labor, time, and testing, and without additional lossof flight time for the aircraft. Because the apparatus for joiningconduits of the present invention may be reused after removal, theconduit system can also be reinstalled without having to replace all ofthe hardware that forms the conduit joint.

The apparatus for joining and sealing conduits, such as ducts, includesedge trim, a sleeve, and a retaining element. The edge trim is shaped tomount upon and engage an end of a conduit. The edge trim is also shapedto extend at least partially along the outer surface of the conduit nearthe end of the conduit, and may extend at least partially along theinner surface of the conduit near the end of the conduit. A ridge mayextend outwardly from the outer surface of the edge trim, near the endof the conduit. The edge trim may be made of an elastomeric material.Alternatively, the edge trim may be made of silicone. In addition, theedge trim may contain reinforcing material

The sleeve extends between the conduits and at least partially surroundsthe edge trim, including the ridge carried by the edge trim. The sleevemay be made of compressible material, such as elastomeric foam orplastic foam, such that when the retaining element surrounds a portionof the sleeve and the edge trim, the retaining element compresses thesleeve. The sleeve also may have a layer of first elastomer-coatedfabric on at least one surface of the sleeve, such as the surface thatfaces the edge trim. Additionally, a layer of material, at least aportion of which has a lower coefficient of friction than the layer offirst elastomer-coated fabric may be located on the side of the sleevethat faces the retaining element contact area to facilitate movement ofthe retaining element over the sleeve at least initially. The portion ofthe material having a lower coefficient of friction than the layer offirst elastomer-coated fabric may be a second elastomer-coated fabric.

In one embodiment, the sleeve has a core, a first layer and a secondlayer. The core region of the sleeve has an inner surface and an outersurface. The core region may be made of plastic foam or an elastomericfoam. The first layer of the sleeve is bonded to the inner surface ofthe core. The first layer may be an elastomer-coated fabric. The secondlayer of the sleeve is bonded to the outer surface of the core and has alower coefficient of friction than the first layer. The first and secondlayers may be longer than the core, such that the first and secondlayers may be bonded together beyond the ends of the core. The sleevealso may include a third layer bonded to the second layer proximate amedial portion of the sleeve for reinforcement of that portion of thesleeve extending between the conduits to prevent the sleeve fromballooning due to pressure inside the conduit during operation of theconduit.

According to the present invention, the method for fabricating thesleeve may include providing the sleeve core having an inner surface andan outer surface, and positioning uncured elastomer-coated fabric thatis longer than the sleeve core on the inner and outer surfaces of thesleeve core. A porous material is placed between the fabric portionsthat extend beyond the sleeve core to ensure that the fabric portionswill not bond, and to allow vapors to escape during curing of the fabricto the sleeve core. The porous material is removed after curing, and thefabric portions that extend beyond the sleeve are then bonded together.The porous material may be made of a breather material and a releasefilm. The method of fabricating the sleeve may also position a band ofuncured elastomer-coated fabric over the fabric that is positioned onthe outer surface of the sleeve core, typically over a medial portion ofthe sleeve core, prior to curing the fabric to the sleeve core. Theuncured elastomer-coated fabric may be silicone coated fabric.

The retaining element surrounds a portion of the sleeve and the edgetrim to hold the sleeve in position with respect to the edge trim. Theretaining element is generally made of a rigid material and may have afirst portion with a first circumference and a second portion with asecond circumference. The first inner circumference may be smaller thanthe second inner circumference and the retaining element may be placedon the sleeve such that the larger second portion is closest to the endof the conduit. If the edge trim has a ridge, the first portion of theretaining element may surround a portion of the sleeve on the side ofthe ridge that is opposite the end of the conduit and the second portionof the retaining element may be near the ridge so as to sandwich aportion of the sleeve therebetween.

In one embodiment of the present invention, the retaining element alsomay have an outwardly extending support having at least one aperture. Atie member may extend through the aperture of the retaining element tolock the retaining element to another retaining element mounted upon anend of another conduit.

The method of joining and sealing conduits of the present inventionincludes mounting the edge trim and a retaining element upon an end of aconduit, such that the retaining element is further from the end of theconduit than the ridge carried by the edge trim. The edge trim also maybe bonded to the conduit during the mounting of the edge trim. Themethod also includes extending a sleeve between the conduits, such thatone end of the sleeve covers the ridge on the edge trim, and sliding theretaining element over the sleeve and toward the ridge, such that aportion of the sleeve is sandwiched between the retaining element andthe ridge.

Sliding the retaining element over the sleeve generally compresses thatportion of the sleeve that underlies the retaining element and displacesthe sleeve material to expand on either side of the retaining element.In sliding the retaining element, the retaining element is generallypositioned such that the retaining element is prevented from moving pastthe ridge toward the end of the conduit and at least partiallyrestrained from moving away from the ridge due to the displaced materialon the side of the retaining element opposite the ridge. In oneembodiment of the present invention, the method also includes the optionof attaching at least one tie member to the retaining element to lockthe retaining element to another retaining element mounted upon an endof another conduit.

As a result of its construction and the corresponding installationmethod, the edge trim, sleeve and retaining element continue to providea tight, leak-proof seal about the conduits as the shape of the conduitsexperience deflection due to internal pressure. Moreover, the apparatusand method of the present invention provide an efficient technique tocouple conduits, while permitting removal for inspection or the like andsubsequent reinstallation, particularly in areas that are difficult toview and/or access.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

Having thus described the invention in general terms, reference will nowbe made to the accompanying drawings, which are not necessarily drawn toscale, and wherein:

FIG. 1 is a cross-sectional view of an apparatus for joining and sealingconduits according to one embodiment of the present invention;

FIG. 2A is a cross-sectional view of the edge trim according to oneembodiment of the present invention;

FIG. 2B is a cross-sectional view of the edge trim according to anotherembodiment of the present invention;

FIG. 3 is a cross-sectional view of the apparatus for joining andsealing conduits according to one embodiment of the present invention,which illustrates one end of a sleeve in more detail;

FIG. 4 is a cross-sectional view of the sleeve according to oneembodiment of the present invention;

FIG. 5 is a cross-sectional view of the sleeve according to anotherembodiment of the present invention; and

FIG. 6 is a cross-sectional view of the retaining element according toone embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. Likenumbers refer to like elements throughout.

In many applications, conduits must be installed to facilitate themovement of liquids, gasses, air, or the like from one location toanother. Frequently, the conduits must be installed in areas where spaceis limited, such that the conduit must be installed in segments, thenjoined and sealed. In addition, because the space is limited, theconduit shape may have to conform to the shape of the area. As such, theconduit may be square, elliptical or some other non-round shape. Duringoperation, however, the shape of a non-round conduit may deflect anddeform into a shape that is somewhat more round due to the internalpressure experienced by the conduit. For example, in aircraft, theenvironmental control system ducts are installed after the aircraft ispartially or totally built, such that the shape of the duct must conformto the available space and the ducts must be installed in pieces. Thus,the segments of the duct must be joined and sealed in the alreadycongested areas of the aircraft where there is little room to access orview the entire duct joint area.

Furthermore, conduits may have to be removed periodically for regularmaintenance and if objects behind the conduits cannot be accessedwithout removing the conduits. For instance, during certain mandatoryaircraft maintenance checks, the environmental control system ducts mustbe removed in order to access the objects behind the ducts andsubsequently reinstalled. Thus, the present invention is advantageous byproviding an apparatus and method for joining conduits of any shape thatwill continue to seal the conduit even if the conduit experiencesdeflection during operation. In addition, the apparatus and method ofthe present invention can be removed and reinstalled in a timely mannerwithout having to replace the conduit or the components of the joiningapparatus. As such, the apparatus and method of the present inventionprovide an efficient and economical way to join and seal conduits inmany applications, including onboard an aircraft, spacecraft or othervehicle, as well as in factories and other buildings.

One embodiment of the apparatus 10 for joining and sealing conduits isshown in FIG. 1. In this embodiment, the apparatus 10 for joining andsealing conduits includes edge trim 12, sleeve 14, and retaining element16 to join the conduits 18. The conduit 18 may be a duct, hose, pipe,tube or the like.

FIGS. 2A and 2B illustrate two embodiments of the edge trim 12. The edgetrim 12 may partially extend about the end of a conduit 18, covering atleast the end and part of the outer surface of the conduit, as shown inFIG. 2A. Alternatively, the edge trim 12 also may cover part of theinner surface of the conduit, as shown in FIG. 2B and FIG. 3, which isanother embodiment of the apparatus 10 for joining and sealing conduitsthat includes the edge trim 12 of FIG. 2B. By at least partiallyextending along the surface of the conduit proximate the end of theconduit, the edge trim 12 provides a smooth surface to support andengage the sleeve 14 and seal the joint. Thus, the edge trim 12 hidesany imperfections in the end of the conduit that, without the edge trim,would cause interference in the seal with the sleeve 14, such asimperfections associated with the material type, termination ofcomposite material plies, weldment of metals, kinking in the conduit,and the like. The edge trim 12 also prevents the elements carried by theconduit 18 from penetrating into the end of the conduit and preventsdelamination of a composite conduit 18. For example, if a honeycombmaterial is contained within the conduit walls and is exposed at the endof the conduit, then the embodiment of the edge trim 12 shown in FIG. 2Bwould prevent moisture penetration into the honeycomb material.Generally, the edge trim 12 is molded to custom fit the shape of the endof the conduit to be joined and sealed, but standard size edge trim maybe made for standard conduit shapes and sizes.

The edge trim 12 also may include a ridge 20, commonly known in theaerospace industry as a bead, extending outwardly from the outer surfaceof the edge trim, near the end of the conduit 18. The ridge 20 is shownon the edge trim in FIGS. 1, 2, and 3. The ridge 20 may extend partiallyor totally about the circumference of the edge trim 12. The ridge 20 mayhave various sizes and shapes depending upon the application, butgenerally has a semicircular or other rounded shape with a heighttypically less than the thickness of the sleeve 14.

The edge trim 12 may be made of any appropriate material. To create thetightest seal between the edge trim 12 and the conduit 18, however, theedge trim 12 may be made of any semi-compressible, damage tolerant andflexible material, such as an elastomeric material. The elastomericmaterial may be silicone or an elastomeric-coated fiberglass fabric. Theproperties of the edge trim 12 may be customized to the specificapplication and environment of the conduit 18. For instance, the edgetrim 12 may be made flame/fire, ballistic, abrasion, impact, solvent,chemical/gas, weather, and/or temperature resistant by selecting theappropriate matrix of materials for the edge trim 12 as will be known tothose skilled in the art, such as flourosilicone, nitrile, neoprene, orother elastomers.

The edge trim 12 also may be partially or totally rigidized by formingthe edge trim of resin impregnated, fiber reinforced fabrics orotherwise integrating resin impregnated, fiber reinforced fabrics withinthe edge trim during fabrication. As FIGS. 2A and 2B illustrate, theouter portion 19 of the edge trim 12 that faces away from the end of theconduit 18 may be rigidized to provide stability about the duct end andto maintain the ridge 20 substantially parallel to the end of theconduit 18. In this situation, the inner portion 21 of the edge trim 12that faces the conduit 18 may be made of any semi-compressible, damagetolerant and flexible material, such as an elastomeric material, inorder to ensure a tight seal between the conduit 18 and the edge trim12.

The type of reinforcement may be selected for the specific environmentalapplication of the edge trim. For example, Nextel™, commerciallyavailable from 3M Corporation, polyester, fiberglass, or aramid, such asKevlar™ commercially available from du Pont de Nemours and CompanyCorporation, fibers may be added as reinforcement depending upon thedesired properties of the edge trim. Futhermore, examples of the resinmaterials are thermoplastic or thermosett materials. The weave patternof the fiber reinforcements may also be selected to achieve adaptabilityin fitting the surface of the conduit 18. For instance, a weave thatallows stretch of the edge trim in one direction while stabilizing theedge trim in other directions, known to those skilled in the art ascrowfoot weave, may be desirable in applications where one edge trim 12will accommodate a variety of conduit thicknesses.

Generally, the elastomeric properties of the edge trim 12 may provideadequate friction to fixedly engage and seal about the end of a conduit18. Alternatively, the edge trim 12 may be bonded to the conduit 18 withany type of compatible adhesive, such as Room Temperature Vulcanized(RTV) adhesive.

The sleeve 14 of the present invention extends between the conduits tobe joined and at least partially surrounds the edge trim 12 on eachconduit 18, as shown in FIG. 1 and FIG. 3. If the edge trim 12 has aridge 20, the sleeve 14 may surround or extend over the ridge 20. Across-sectional view of one embodiment of the sleeve 14 of the presentinvention is shown in FIG. 4. While the sleeve may be constructed indifferent manners, the sleeve 14 of this embodiment contains a core 22,an outer layer 24, and an inner layer 26. The core 22 of this embodimentmay be made of any elastomeric or plastic foam, depending upon thespecific application and/or environment of the conduit 18. For example,the core 22 may be made of self-skinning cellular silicone foam inapplications where controlled compression, rebound resilience, heatresistance, oxidation resistance, and ozone attach resistance isdesirable.

To enhance the fluid resistance and friction between the sleeve 14, theedge trim 12 and, in some embodiments, the retaining element 16, anouter layer 24 and inner layer 26 may be bonded to the core 22. Thelayers 24, 26 may be made of any suitable elastomer coated on a suitablefabric, the specific properties of which are chosen depending upon theapplication and environment of the conduit 18. For example, both theouter and inner layers 24, 26 may be made of an elastomer-coated fabric,such as a fabric coated with a flouroelastomer, that provides a highcoefficient of friction between the sleeve 14 and the components oneither side of the sleeve 14. Alternatively, the inner layer 26 may bemade of an elastomer-coated fabric with a high coefficient of friction,in order to hold the sleeve 14 on the conduit 18 and/or edge trim 12,while the outer layer 24 may be at least partially made of a lowfriction material, such as Teflon™ commercially available from du Pontde Nemours and Company Corporation, in order to at least initially slidethe retaining ring 16 over the sleeve 14 without difficulty.

The uncured elastomers coated on a fabric may be rubber, rubber-based orsilicone material. For a high coefficient of friction, the elastomersmay be coated on a fiberglass or other suitable fabric. One example ofan elastomer-coated fabric having a relatively high coefficient offriction, particularly when mated with substrate materials, is thefluoroelastomer Viton™, commercially available from du Pont de Nemoursand Company Corporation. For a material with a lower coefficient offriction, the elastomers may be coated on a polyester, aramid, such asKevlar™ commercially available from du Pont de Nemours and CompanyCorporation, Nextel™ commercially available from 3M Corporation, or anyother suitable fabric for the specific application. In addition, toobtain the desired amount of stretch in the layers, the fibers in thefabric may be oriented from a bias position (more stretch) to a non-biasposition (less stretch). Bias fabric is made of wrap and fill fibersgenerally at a 45 degree angle to the length of the fabric, whichenables the fabric to stretch in essentially any direction. Non-biasfabric is made from wrap and fill fibers in which the wrap fibers aregenerally parallel to the length of the fabric and perpendicular to thefill fibers. Non-bias fabric stretches essentially only in the wrap andfill directions, but non-bias fabric may be cut diagonally to the lengthof the fabric to produce a fabric with bias characteristics. Forexample, to prevent deflection of the sleeve 14 between the conduits 18due to internal pressure during operation, the outer and/or inner layer24, 26 may be made of elastomers coated on a non-bias material, suchthat the outer layer prevents the sleeve from stretching, and, thus,prevents deflection.

FIG. 5 illustrates another embodiment of the sleeve 14 of the presentinvention. This embodiment illustrates that a third layer or band 28 maybe positioned at or near the middle of the sleeve 14 over the outerlayer 24. The band 28 may be made of the same material as the outerlayer 24, as described above. The band 28 may be placed on the sleeve 14in order to prevent deflection of the sleeve 14 between the conduitsand, as such, it may be desirable for the band 28 to be made of uncuredelastomers coated on a non-bias fabric to prevent or significantlyreduce ballooning/stretching of the sleeve in the joint area between theconduits 18. If the outer layer 24 is also made of a non-bias fabric,the band 28, provides additional deflection prevention.

FIG. 5 also illustrates that the outer and inner layers, 24, 26, may belonger than the core 22, such that the layers may completely surroundthe core 22. The regions 30 of the outer and inner layers, 24, 26, thatare longer than the core may be utilized in installation of the sleeve14 as an area to grasp and pull the sleeve 14 over the edge trim 12and/or conduit 18.

To bond the layers 24, 26 to the core 22 and, optionally, the band 28 tothe outer layer 24, the layers are first positioned on the core 22 inthe orientation shown in FIGS. 4 and 5. The oriented layers 24, 26 andthe core 22 may be placed about a tool that has the general shape of thedesired sleeve 14. The tool is preferably hollow in order to more evenlydistribute the heat during the curing process and for ease of removal ofthe cured sleeve 14 from the tool. The layers 24, 26 and the core 22 maybe flat sheets of material that are spliced along the length of thematerial in order to form the sleeve-shape, or the layers may bepre-molded in the sleeve-shape. Prior to placing the layers 24, 26 andcore 22 on the tool, a release material may be applied to tool toprevent the inner layer 26 from bonding to the tool during the heat-cureprocess. The release material may be a mold release spray, such asFrekote 44NC, commercially available from Dexter Corp., or anon-permeable release film, such as films available from AirtechInternational, Inc. and Hawkeye Enterprises, Inc. The layers 24, 26 andcore 22 then may be placed on the tool after splicing or they may bespliced after being positioned on the tool.

A porous material, which in one embodiment of the present inventioncomprises a breather material and a permeable release film, is placedbetween the regions of the layers 24, 26 that extend past the core 22.Examples of the breather material include Airweave N10, commerciallyavailable from Airtech International, Inc., and Resin Bleeder 3000A-10,commercially available from Hawkeye Enterprises, Inc. Examples of thepermeable release film include permeable resin release film,commercially available from Chemfab Corp. and Richmond AircraftProducts, Inc., and permeable gas release film, commercially availablefrom National Aerospace Supply Co., Chemfab Corp., and NortonPerformance Plastics. The porous material prevents vulcanization of thelayers 24, 26 during the heat-cure process. The porous material alsopermits gases to escape during heat-cure process, enabling bondingbetween the layers 24, 26 and the core 22. Without the porous material,the trapped gases may disadvantageously prevent bonding between thelayers 24, 26 and the core 22.

Once the layers 24, 26 and core 22 are oriented and positioned on thetool, a layer of porous material, which may be layers of breathermaterial and permeable release film, as described above, may be placedover the outer layer 24. A wrap, such as a shrink tape wrap or a vacuumbag, may be placed about the porous material, which prevents the wrapfrom bonding to the outer layer 24 during the heat-cure process. Thetool with the layers of materials may then be heat-cured in order tobond the layers 24, 26 to the core 22 and, thus, produce the sleeve 14.After heat-curing, the wrap is removed from the outer layer 24. Theporous material(s) may also be removed, and the layers 24, 26 may bebonded together with any type of compatible adhesive, such as RoomTemperature Vulcanized (RTV) adhesive. A specific example is RTV 106 orRTV 732. The sleeve may be removed from the tool at any time after theheat-cure process has concluded.

The retaining element 16 is formed to surround a portion of the sleeve14 and edge trim 12 that are positioned on the conduit 18, in order tohold the sleeve 14 in position with respect to the edge trim 12. Theshape of the retaining element 16 may be customized to match the shapeof the conduit 18. The retaining element 16 may be made of a rigidmaterial, such that the retaining element 16 firmly and uniformlyengages the sleeve 14 and edge trim 12 to provide a seal about the endof the conduit 18. The rigid characteristic of the retaining element 16also prevents the deflection of the conduit 18 due to internal pressurein the conduit 18, at least near the end of the conduit 18. Theanti-deflection feature of the retaining element 16 also adds to theleak-proof nature of the seal created by the retaining element 16 andthe other components joining the conduits 18. The retaining element 16exterts a force on the conduit 18 and the deflection of the conduit 18exerts an oppositely directed force on the retaining element 16 and theother components, providing a tight seal about the end of the conduit.

The retaining element 16 may be made by a process and from materials,chosen by assessing a variety of factors, such as weight requirements,cost of material, cost of the tools, and quantity. For example, theretaining element 16 may be made of a composite material, fabricated bylaminating multiple plies of resin pre-impregnated fiberglass cloth on ametal tool, i.e. a mandrel, defining the shape of the retaining elementand oven cured under heat and pressure. Once the retaining element 16 iscured, it may be trimmed to meet the specific design dimensions of theapplication. Other examples of processes and materials for making theretaining element include injection-molded thermoplastics, compressionmolded thermoset plastics, and machined, cast and rolled formed metals.

One embodiment of the retaining element 16 may have a first portion 32and a second portion 34 with first and second inner circumferences,respectively. This embodiment of the retaining element is shown in thecross-sectional views of the apparatus for joining and sealing conduitsin FIG. 1 and FIG. 3, and in the cross-sectional view of the retainingelement in FIG. 6. The first inner circumference is smaller than thesecond inner circumference, and when the retaining element 16 ispositioned on the sleeve, the larger second portion 34 is closest to theend of the conduit 18. In addition, if the edge trim 12 has a ridge 20,the second portion 34 may engage the ridge 20, such that the retainingelement 16 is prevented from moving past the ridge 20 toward the end ofthe conduit 18.

If the sleeve 14 is made of a compressible material, as discussedhereinabove, then the first portion 32 of the retaining element ispreferably sized to be smaller than the nominal, uncompressed size ofthe sleeve 14, but once the sleeve 14 is mounted upon the conduit 18,equal to or slightly larger than the resulting size if the sleeve 14were fully compressed. As such, one retaining element 16 generallycompresses the sleeve 14 as it is moved toward the end of the conduit18. Therefore, when the retaining element is in place near the end ofthe conduit 18, the sleeve 14 may be compressed under at least the firstportion 32 of the retaining element 16. Th portions of the sleeve 14 onopposite sides of the first portion 32 of the retaining element 16 aretypically uncompressed. The uncompressed portion or portions 36 of thesleeve 14 then may at least partially restrain or discourage theretaining element 16 from moving, at least in the direction away fromthe end of the conduit 18, once the retaining element 16 is in place.

The retaining element 16 may also include at least one outwardlyextending support 38. The support 38 prevents or further limits outwarddeflection of the retaining element 16 to ensure a tight seal. Thesupport 38 may also have an aperture 40, as shown in FIG. 6, such that atie member 42, as shown in FIG. 1, may extend through the aperture 40 ofone retaining element 16 mounted upon a conduit 18 as well as theaperture 40 of another retaining element 16 mounted upon another conduit18 to lock the retaining elements together and prevent the retainingelements from moving away from the ends of the conduits 18.

To join conduits according to the method of the present invention, theedge trim 12 and the retaining element 16 are mounted upon an end ofeach respective conduit 18. The edge trim 12 may be bonded to theconduit 18 or the coefficient of friction of the material of the edgetrim 12 may be sufficient to hold the edge trim 12 on the conduit 18. Ifthe edge trim 12 has a ridge 20, the retaining element 16 is placedfurther from the end of the conduit 18 than the ridge 20. The sleeve 14may then be extended between the conduits 18 to at least partially coverthe edge trim 12. If the edge trim 12 has a ridge 20, then one end ofthe sleeve 14 may cover the ridge 20. The retaining element 16 is thenslid over the sleeve 14 toward the end of the respective conduit 18 soas to sandwich the sleeve 14 between the retaining element 16 and theedge trim 12. If the edge trim 12 has a ridge 20, then the retainingelement 16 is slid over the sleeve 14 toward the ridge 20, such that aportion of the sleeve 14 is sandwiched between the retaining element 16and the ridge 20.

As described above, if the sleeve 14 is made of a compressible material,then the retaining element 16 compresses the portion of the sleeve 14underlying the first portion 32 of the retaining element 16, and theuncompressed portion of the sleeve 36 may serve to restrict furthermovement of the retaining element 16. To further limit movement of theretaining elements 16, the retaining elements 16 may be attached to eachother by a tie member, as also described above.

Once the components are positioned on the conduits 18 as describedabove, a seal is created about the conduits 18. The seal is made eventighter when the conduits 18 are in operation and experience internalpressure, because the internal pressure deflects the conduit 18 outwardand creates a force that is offset by and opposite to the force on theconduit 18 created by the edge trim 12, sleeve 14 and retaining element16.

Thus, the apparatus and method of the present invention provides aneconomical and effective way to join and seal conduits. The apparatus ofthe present invention creates a seal about the ends of the conduitsthrough a combination of components designed to work together by theirshape and their material properties. In addition, the properties andcharacteristics of the components utilize the inherent nature of theconduits to deflect during operation to create an even stronger seal,unlike the conventional sealing methods in which deflection of theconduits typically causes a break in the seal and leakage of theelements carried by the conduits. The apparatus for joining and sealingconduits of the present invention is also much easier to mount uponconduits than the conventional system because the components arepre-made and designed to fit snuggly about the conduits with verylittle, if any, adhesive, reducing the time and effort that must beexpended by an installer. Furthermore, the apparatus and method of thepresent invention provide components to join and seal conduits that maybe removed and reinstalled without damaging the conduit or thecomponents, which significantly decreases the cost and time involvedwhen removing conduits during maintenance checks or otherwise.

Many modifications and other embodiments of the invention will come tomind to one skilled in the art to which this invention pertains havingthe benefit of the teachings presented in the foregoing descriptions andthe associated drawings. Therefore, it is to be understood that theinvention is not to be limited to the specific embodiments disclosed andthat modifications and other embodiments are intended to be includedwithin the scope of the appended claims. Although specific terms areemployed herein, they are used in a generic and descriptive sense onlyand not for purposes of limitation.

1. A method of fabricating a sleeve for joining and sealing conduits,comprising: providing a sleeve core having an inner surface and an outersurface; positioning an uncured elastomer-coated fabric on the innersurface and the outer surface of the sleeve core, such that portions ofthe fabric extend beyond the sleeve core; placing a porous materialbetween the fabric portions that extend beyond the sleeve core; curingthe fabric to the sleeve core; removing the porous material; and bondingthe fabric portions that extend beyond the sleeve core.
 2. The method ofclaim 1, further comprising positioning a band of uncuredelastomer-coated fabric over the uncured elastomer-coated fabricpositioned on the outer surface of the sleeve core prior to curing thefabric to the sleeve core.
 3. The method of claim 1, wherein positioninguncured elastomer-coated fabric comprises positioning silicone coatedfabric.
 4. The method of claim 1, wherein placing the porous materialcomprises placing a breather material and a release film between thefabric portions that extend beyond the sleeve core, and wherein removingthe porous material comprises removing the breather material and therelease film.